(1) Field of the Invention
The present invention relates to catalyst carriers made of a metallic material (hereinafter referred to as "metallic catalyst carriers") to be used for purification catalysts to purify combustion waste gases exhausted from automobiles and factories. The invention also relates to a process for producing such catalyst carriers.
(2) Related Art Statement
Heretofore, Japanese Patent Application Laid-open No. 56-96,726 discloses a technique using, as metallic catalyst carriers, a foil made of an aluminum-containing ferrite type stainless steel in which alumina whiskers are formed on surfaces of the foil through heat treatment. According to this technique, a stainless steel which can withstand high temperatures is used, and a alumina whiskers are present on its surface. Therefore, when .gamma.-Al.sub.2 O.sub.3 or the like is carried on such a catalyst carrier as a wash coat, the alumina whiskers function as wedges. Thus, the wash coat layer made of .gamma.-Al.sub.2 O.sub.3 or the like can firmly be adhered to the metallic catalyst carrier.
However, since the ferrite type stainless steel used as the substrate contains not less than 3% by weight of aluminum, its plastic deformability is extremely deteriorated. Thus, it takes many steps to obtain a foil of the stainless steel of this kind.